In fixing a different timing related bug, #3887, a new bug was introduced causing I2C reads longer than 255 bytes to timeout for some I2C devices, #3888.
The issue was caused by incorrect branch order, and poll function being called unnecessarily.
Async I2C read poll function now only looks for I2C transfer complete reload (TCR) interrupts, intead of TCR and transfer complete (TC) interrupts,
since TC interrupts are not raised when AUTOEND bit is set.
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